1. Field of the Invention
This invention relates to a method for chemically mechanically polishing an organic film such as a resist film, to a method of manufacturing a semiconductor device, and to a program for the chemically mechanically polishing.
2. Description of the Related Art
In the process of manufacturing a semiconductor device, a resist film is employed as a sacrificial film for forming a desired structure. For example, subsequent to the formation of a trench in a semiconductor substrate or the formation of a hole in an insulating film, a resist is coated to form a sacrificial film, which is then recessed or partially removed to obtain a desired structure. This method is employed specifically for forming a buried strap for providing an electric connection between a storage node electrode and a cell transistor diffusion region in the manufacture of a semiconductor memory device having a trench capacitor. This method is also useful for preforming, in the process of forming a Cu dual damascene (Cu DD) structure, a via-hole (via first DD).
In either cases, the film thickness of the resist film is required to be uniform throughout a wafer. However, if resist is to be buried in a trench or hole of high patterning density, the volume of resist disposed on a pattern of high density is reduced. Because of this, variability in the order of several hundreds nanometers is generated between the film thickness of the resist film on a pattern of high density and the film thickness of the resist film on a pattern of low density or on a field region.
This variability in film thickness of resist will be further increased in a step of forming a recess which will be executed subsequently, thus degrading the configuration of device and hence resulting in the decrease of depth of focus as well as in the deterioration of yield. With a view to overcome the aforementioned problems due to the variability in film thickness of resist film, there has been proposed a method wherein polishing is performed with a polishing head and a polishing pad being rotated at a low rotational speed of 30 rpm or so. Namely, in the CMP of a hydrophobic film such as a resist film, it is difficult to maintain friction, and, therefore, it is generally difficult to secure a practical polishing speed. Under the circumstances, the polishing is performed at a boundary lubrication region in a Stribeck diagram with a polishing head and a polishing pad being rotated at a low rotational speed, thereby making it possible to retain high friction between a polishing pad and a semiconductor substrate held on a polishing head so as to increase polishing speed and to realize a stable polishing of a resist film within a short period of time. However, even with this conventional method, the improvement of friction is limited.